FR3043716A1 - VARIABLE DISTRIBUTION ASSEMBLY FOR AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

The invention relates to a variable valve assembly for an internal combustion engine comprising an inner shaft (1), an outer shaft (2) concentrically mounted to the inner shaft (1), the outer shaft (2) being rotatable relative to the inner shaft (1), a cam (3) disposed on the outer shaft (2), movable about a longitudinal axis (Z) of the outer shaft (2), said cam (3) comprising means fixing and driving which connect the cam (3) to the internal shaft (1) through a slot (9) of the outer shaft (2), characterized in that it comprises a ring (6) comprising a target (7) for reading the angular position of the internal camshaft (1), this ring (6) being also held by the fixing means connecting the cam (3) to the internal shaft (1) .

Description

VARIABLE DISTRIBUTION ASSEMBLY FOR A COMBUSTION ENGINE

INTERNAL

The present invention relates to the field of internal combustion engines. The invention more particularly relates to a variable distribution assembly for an internal combustion engine.

The new engines must respond to a problem that is becoming more and more restrictive, in particular regulatory limits for pollutant emissions and increasingly severe C02 emissions.

These constraints push us to optimize the heat engine in its operation, and this, for all its phases of life.

Among the technologies used for this purpose, the variable distribution allows better performance and less pollution by varying parameters such as angular setting, the duration of opening and / or the lifting of the intake and exhaust valves.

For example, document US20120160197 discloses a variable distribution device comprising an internal camshaft and an outer camshaft, the two shafts being concentric. In this device, the internal shaft is out of phase with the external shaft which is connected to the crankshaft.

One of the difficulties of this technology is to integrate a target to read the position of the internal camshaft.

US20120160197 proposes to place for example the target at the end of the internal camshaft or still on the phase shifter, coupled to the inner part which shifts. However, such implantations generate excessive construction and assembly costs.

Therefore, the problem underlying the invention is to achieve a variable distribution set with a target implanted at a lower cost. Another object of the invention is to avoid a diversity on the cams, which also induces a higher cost.

To solve this problem, there is provided according to the invention a variable distribution assembly for an internal combustion engine comprising: an internal shaft, an external shaft mounted concentrically to the internal shaft, this external shaft being rotatable relative to the internal shaft, a cam disposed on the outer shaft, movable about a longitudinal axis of the outer shaft, the cam comprising: fixing and driving means which connect the cam to the internal shaft to through a light of the external shaft, characterized in that it comprises a ring comprising a target for reading the angular position of the internal camshaft, this ring being also held by the fixing means connecting the cam to the internal shaft. The technical effect is to mutualize the fastening means to the fixing of the movable cam and the ring carrying the target, which allows a saving of workpiece and mounting operation.

Various additional features may be provided, alone or in combinations:

In a variant, the fastening fastening and driving means are formed by a pin.

In another variant, the movable cam comprises a first portion carrying a lever profile of a motor valve and a second portion, adjacent to the first portion and carrying a passage hole of the fixing and driving means.

In another variant, the ring comprises a first portion carrying the target and a second portion carrying a passage hole of the fastening and driving means.

In a variant, the second portion of the ring concentrically overlaps the second portion of the movable cam.

In another variant, the assembly comprises a plurality of moving cams and the ring is assembled with the most end movable cam of the external shaft, preferably at the end of the outer shaft intended to be connected to a distribution pulley of the engine.

In a variant, the target is positioned between the endmost movable cam of the outer shaft and the same outer shaft end. The invention also relates to a method of mounting a variable distribution assembly according to the latter variant, the assembly comprising a plurality of moving cams and a plurality of cams mounted fixed on the outer shaft, characterized in that it comprises the steps of: -on the external shaft, alternation of fitting of a fixed cam and sliding of a movable cam, -on the last movable cam slid, establishment of the ring carrying the target, -Insertion of the internal shaft in the external shaft, -for mobile cam without ring, fitting of their pins to immobilize the cams movable relative to the inner shaft, - for the movable cam bearing the ring, fitting of its pin to immobilize this cam and the ring relative to the internal shaft. The invention also relates to an internal combustion engine, characterized in that it comprises a variable distribution assembly according to one of the previously described variants. The invention also relates to a vehicle, characterized in that it comprises such an internal combustion engine. Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, with reference to the figures in which: - Figure 1 is a schematic representation exploded d a variable timing assembly for an internal combustion engine according to the invention. - Figure 2 is a schematic representation of the assembly between the movable cam, the target carrier ring and the inner shaft and the outer shaft. FIG. 3a and FIG. 3b illustrate two steps of mounting a variable distribution assembly for an internal combustion engine according to the invention.

Figure 1 shows an exploded view of a variable distribution assembly embodiment for an internal combustion engine of the invention. Such a variable timing assembly is suitable for an internal combustion engine whose intake and / or exhaust valves are driven by cams. Such an engine can equip a vehicle.

In this FIG. 1, the reference 1 designates an internal shaft and the reference 2 a hollow external shaft extending along a longitudinal axis Z. The external shaft 2 is mounted concentrically to the internal shaft 1, this external shaft 2 being able to rotate relative to the internal shaft 1. The external shaft 2 which serves as a reference is intended to be connected to a distribution pulley itself connected to the crankshaft of the engine by flexible transmission means such as a belt or a chain, the internal shaft 1 is intended to be connected to a phase shifter enabling the rotation of the internal shaft 1 in rotation about the longitudinal axis Z to apply a predetermined angular offset with respect to the external shaft 2.

On the outer shaft 2 are rigidly fixed cams 10. The cams 10 may for example be fitted on the outer shaft 2. In FIG. 1, four fixed cams 10 are shown, each intended to control the movement of an intake or exhaust valve of a cylinder of the cylinder. engine. The variable distribution assembly presented in FIG. 1 is therefore suitable for a four-cylinder internal combustion engine. The number of cams of the variable distribution assembly of the invention can be adapted to an internal combustion engine comprising a different number of cylinders, for example three cylinders.

On the outer shaft 2 are also arranged cams 3 movable each for the control of the movement of another intake valve or exhaust cylinder of the engine. In FIG. 1, four moving cams 3 are shown, each intended to control the movement of another intake or exhaust valve of a cylinder of the engine.

The cams 3 are movable in that they can rotate over a determined angular range around the outer shaft 2.

Each cam 3 is mechanically connected to the internal shaft 1, by means for fixing and driving this cam 3 to the internal shaft 1. These fixing and driving means connect the cam 3 to the shaft internal 1 passing through a light 9 arranged in the outer shaft 2.

For the sake of simplicity of mechanical realization, these fixing and driving means are formed by a pin 8.

According to the invention, with reference also to FIG. 2, the variable distribution assembly further comprises a ring 6 bearing on a first annular portion 6a, a target 7 for reading the angular position of the camshaft This ring 6 is also held by the pin 8. In this arrangement, the same pin 8 allows the attachment and the rotational drive of both the movable cam 3 and the ring 6 carrying the target 7.

The target 7 may comprise teeth whose detection of the presence makes it possible to determine the angular position of the internal shaft 1. The target 7 may advantageously be a magnetic track, which is more compact than a toothing.

Referring again to Figure 2, the movable cam 3 comprises two adjacent portions 4 and 5. The first 4 part of the cam 3 carries a lever profile of the valve whose movement is controlled by the cam 3. The second part 5 , having the shape of a ring carries a hole 11 through which is inserted in force the pin 8 to immobilize and position the cam 3 movable relative to the inner shaft 1.

The ring comprises a second portion 6b, adjacent to the first portion 6a carrying the target 7. This second portion 6b also carries an orifice 12 in which is inserted by force the pin 8 to immobilize and position the ring 6 relative to the shaft The second portion 6b of the ring 6 concentrically overlaps the second portion 5 of the movable cam 3.

The light 9 is open in the outer shaft 2 perpendicular to the longitudinal axis Z is arranged to allow the movement of the pin 8 and thus the rotation of the inner shaft 1 over a given angular range, for example 60 ° .

The ring 6 may be sheet metal, with a magnetic target 7 reported and glued to the first portion 6a. The ring 6 can be made differently, for example by sintering.

Returning to FIG. 1, when the internal shaft drives a plurality of movable cams 3, the ring 6 carrying the target 7 is preferably assembled with the movable cam 3 situated at the end of the outer shaft 2, which allows improve the accuracy of reading. More preferably it is the external shaft end 2 intended to be connected to the distribution pulley, Thus the target is closer to the distribution drive to a place where the twist is less than on the other cams, which improves reading accuracy. More preferably, the target 7 is oriented outwardly of the outer shaft 2, in other words the target 7 is positioned between this movable cam 3 and this outer shaft end 2.

The assembly of an assembly as shown in FIG. 1 is as follows: on the external shaft 2, alternation of fitting of a fixed cam 10 and sliding cam 3, on the last movable cam 3 sliding, setting up the ring 6 carrying the target 7 (FIG. 3a) -Insertion of the internal shaft 2 into the external shaft 2, -Embracing of the pins 8 to immobilize the moving cams 3 without a ring with respect to the internal shaft 1, -Emgling a pin 8 for the cam 3 movable carrying the ring 6 to immobilize the cam and the ring 6 relative to the inner shaft 1 (Figure 3b).

In order to improve the standardization of the parts, the mobile cams 3 not bearing the ring 6 are identical to the cam bearing the ring 6. Due to the extra thickness of the ring 6, the pin 8 intended to immobilize the assembled movable cam 3 with the ring 6 may be longer than the other pins. Alternatively, in order to improve the standardization of the parts, the pins 8 can be of the same length. The invention makes it possible to integrate a target on the out-of-phase cam in an easily implantable and easy to mount manner, without generating diversity on the cams.

Claims (10)

claims A variable timing assembly for an internal combustion engine comprising: an inner shaft (1); an outer shaft (2) concentrically mounted to the inner shaft (1), which outer shaft (2) is rotatable relative to the shaft internal (1), -a cam (3) disposed on the outer shaft (2), movable about a longitudinal axis (Z) of the outer shaft (2), the cam (3) comprising: -means fixing and driving which connect the cam (3) to the internal shaft (1) through a slot (9) of the outer shaft (2), characterized in that it comprises a ring (6) comprising a target (7) for reading the angular position of the internal camshaft (1), this ring (6) being also held by the fixing means connecting the cam (3) to the internal shaft (1) . 2. An assembly according to claim 1, characterized in that the fixing and driving means are formed by a pin (8). 3. An assembly according to any one of the preceding claims, characterized in that the cam (3) movable comprises a first portion (4) carrying a lever profile of a motor valve and a second portion (5), adjacent to the first part and carrying a hole (11) for passing fastening and driving means. 4. An assembly according to any one of the preceding claims, characterized in that the ring (6) comprises a first portion (6a) carrying the target (7) and a second portion (6b) carrying a hole (12) for passage of fastening and training means. 5. An assembly according to claims 3 and 4, characterized in that the second portion (6b) of the ring (6) concentrically overlaps the second portion (5) of the cam (3) movable. 6. An assembly according to any one of the preceding claims, characterized in that it comprises a plurality of cams (3) movable and the ring (6) is assembled with the cam (3) mobile most end of the outer shaft ( 2), preferably at the end of the external shaft (2) intended to be connected to a motor distribution pulley. 7. An assembly according to the preceding claim, cargetirisé in that the target (7) is positioned between the cam (3) movable most end of the outer shaft (2) and the same end of the outer shaft (2). 8. A method of mounting a variable distribution assembly according to claim 7, the assembly comprising a plurality of cams (3) movable and several cams (10) fixedly mounted on the outer shaft (2) characterized in that it comprises the steps of: -on the external shaft (2), alternating fitting of a cam (10) fixed and sliding of a cam (3) movable, -on the last cam (3) slid mobile, put in place of the ring (6) carrying the target (7), -Insertion of the internal shaft (1) in the external shaft (2), -for the cams (3) movable without ring, fitting of their pins ( 8) to immobilize the cams (3) movable relative to the inner shaft (1), - for the cam (3) movable carrying the ring (6), fitting of its pin (8) to immobilize this cam and the ring (6) relative to the internal shaft 1. 9. Internal combustion engine, characterized in that it comprises a variable distribution assembly according to one of claims 1 to 8. 10. Vehicle, characterized in that it comprises an internal combustion engine according to the preceding claim.